Adding spacebar handler to make editing combobox column easier. (#1516)

Addresses part of #1284

Author: Keboo

MainDemo.Wpf/Grids.xaml

@@ -1,4 +1,4 @@
-<UserControl x:Class="MaterialDesignColors.WpfExample.Grids"
+<UserControl x:Class="MaterialDesignColors.WpfExample.Grids"
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
@@ -46,7 +46,7 @@
                                                            Header="Description"
                                                            MaxLength="255" 
                                                            EditingElementStyle="{StaticResource MaterialDesignDataGridTextColumnPopupEditingStyle}"  />
-                            <materialDesign:DataGridTextColumn Binding="{Binding Numeric}"
+                        <materialDesign:DataGridTextColumn Binding="{Binding Numeric}"
                                                         Header="Number with long header"
                                                         Width="120"
                                                         EditingElementStyle="{StaticResource MaterialDesignDataGridTextColumnPopupEditingStyle}">
@@ -71,8 +71,8 @@
 
                         <!-- use custom combo box column to get better combos. Use ItemsSourceBinding as your binding template to be applied to each combo -->
                         <materialDesign:DataGridComboBoxColumn Header="Food" IsEditable="True"
-                                                                   SelectedValueBinding="{Binding Food}"
-                                                                   ItemsSourceBinding="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type DataGrid}}, Path=DataContext.Foods}">
+                                                               SelectedValueBinding="{Binding Food}"
+                                                               ItemsSourceBinding="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type DataGrid}}, Path=DataContext.Foods}">
                             <!--Setting the editing element style allows access to all of the combo box's properties
                             <materialDesign:MaterialDataGridComboBoxColumn.EditingElementStyle>
                                 <Style TargetType="ComboBox" BasedOn="{StaticResource {ComponentResourceKey TypeInTargetAssembly={x:Type ComboBox}, ResourceId=MaterialDataGridComboBoxColumnEditingStyle}}" >

MaterialDesignThemes.Wpf/DataGridAssist.cs

@@ -144,9 +144,27 @@ private static void EnableCheckBoxAssistPropertyChangedCallback(DependencyObject
             if (dataGrid == null) return;
 
             if ((bool) dependencyPropertyChangedEventArgs.NewValue)
+            {
                 dataGrid.PreviewMouseLeftButtonDown += DataGridOnPreviewMouseLeftButtonDown;
+                dataGrid.KeyDown += DataGridOnKeyDown;
+            }
             else
+            {
                 dataGrid.PreviewMouseLeftButtonDown -= DataGridOnPreviewMouseLeftButtonDown;
+                dataGrid.KeyDown -= DataGridOnKeyDown;
+            }
+        }
+
+        private static void DataGridOnKeyDown(object sender, KeyEventArgs e)
+        {
+            if (e.Key == Key.Space &&
+                e.OriginalSource is DataGridCell cell &&
+                cell.IsReadOnly == false &&
+                cell.Column is DataGridComboBoxColumn &&
+                sender is DataGrid dataGrid)
+            {
+                dataGrid.BeginEdit();
+            }
         }
 
         private static void DataGridOnPreviewMouseLeftButtonDown(object sender,
@@ -159,7 +177,7 @@ private static void DataGridOnPreviewMouseLeftButtonDown(object sender,
 
             while (inputHitTest != null)
             {
-                var dataGridCell = inputHitTest as DataGridCell;                
+                var dataGridCell = inputHitTest as DataGridCell;
                 if (dataGridCell != null && dataGrid.Equals(dataGridCell.GetVisualAncestry().OfType<DataGrid>().FirstOrDefault()))
                 {
                     if (dataGridCell.IsReadOnly) return;